Molecular dynamics
simulation of DNA sequencing through a graphene nanopore.
Cytosine molecules
(white) linked to nanopore detect guanine (green) in vertical
DNA strand. Inset
shows graphene deflection over time.
Credit: T.A.
Wassenaar/Univ. Groningen; A.F. Kazakov and A. Smolyanitsky/NIST.
(January 15, 2016) Researchers
at the National Institute of Standards and Technology (NIST) have simulated a
new concept for rapid, accurate gene sequencing by pulling a DNA molecule
through a tiny, chemically activated hole in graphene—an ultrathin sheet of
carbon atoms—and detecting changes in electrical current.
The NIST study suggests the method could identify about 66
billion bases—the smallest units of genetic information—per second with 90
percent accuracy and no false positives. If demonstrated experimentally, the
NIST method might ultimately be faster and cheaper than conventional DNA
sequencing, meeting a critical need for applications such as forensics.
Conventional sequencing, developed in the 1970s, involves
separating, copying, labeling and reassembling pieces of DNA to read the
genetic information. The new NIST proposal is a twist on the more recent
“nanopore sequencing” idea of pulling DNA through a hole in specific materials,
originally a protein. This concept—pioneered 20 years ago at NIST—is based on
the passage of electrically charged particles (ions) through the pore. The idea
remains popular but poses challenges such as unwanted electrical noise, or
interference, and inadequate selectivity.
By contrast, NIST’s new proposal is to create temporary
chemical bonds and rely on graphene’s capability to convert the mechanical
strains from breaking those bonds into measurable blips in electrical
current.
"This is essentially a tiny strain sensor,” says NIST
theorist Alex Smolyanitsky, who came up with the idea and led the project. “We
did not invent a complete technology. We outlined a new physical principle that
can potentially be far superior to anything else out there.”